Abstract
Purpose: :
To examine the prevalence of type 2 idiopathic macular telangiectasia (IMT) and lesions characterizing IMT in a population-based cohort study.
Methods: :
As part of the Beaver Dam Eye Study, 4926 persons between the ages of 43 and 86 years were examined from 1988-1990. A standardized examination, questionnaire and stereoscopic fundus photographs were collected for all study participants. The fundus photographs were subsequently graded for the following IMT lesions: loss of retinal transparency, pseudohole or yellow spot in the fovea, crystals in the inner retinal layers, blunted retinal vessels, localized pigment migration and depigmentation and the presence of telangiectatic vessels in the juxtafoveolar region. Eyes with epiretinal membranes with traction on the retina or eyes with signs of age-related macular degeneration (AMD) resulting in increased retinal pigment or RPE depigmentation or atrophy were excluded. Data from 4780 people (97.0%) had at least one eye with gradable fundus photographs for IMT included in the analyses.
Results: :
IMT was present at baseline in 0.1% of the population (95% Confidence Interval [CI] 0.09, 0.1). The frequencies of loss of retinal transparency, crystals, blunted retinal vessels, and pigment clumping and depigmentation in the juxtafoveolar region and the presence of yellow deposits and pseudoholes in the foveal area in those without IMT varied from 0.06% for retinal telangiectatic vessels to 1.2% for pseudoholes. Smoking was associated with pigment clumping (Odds Ratio [OR] per pack year 1.02; 95% CI 1.00, 1.03; P=0.02), RPE depigmentation (OR 1.02 per pack year; 95% CI 1.00, 1.04; P=0.02), loss of transparency (OR 1.02 per pack year; 95% CI 1.00, 1.03; P=0.008) and the presence of a yellow spot in the fovea (OR 2.24 current vs. never smoker; 95% CI 1.29, 3.89; P=0.004) but not with presence of IMT (OR 2.72; 95% CI 0.45, 16.28; P=0.27).
Conclusions: :
To our knowledge, these are the first population-based data describing the prevalence of IMT (0.1%) and lesions characterizing it. These data are useful in estimating the burden of this condition in the population. The role of smoking in the development of IMT requires further study.
Keywords: clinical (human) or epidemiologic studies: prevalence/incidence • clinical (human) or epidemiologic studies: risk factor assessment • retinal degenerations: hereditary